This invention relates generally to a valve for controlling fuel oil supplied from a fuel pump to the nozzle of an oil burner.
A system of the type in which the present valve is particularly adapted for use is disclosed in Swedberg U.S. Pat. No. 3,566,901. In such a system, a pump delivers pressurized fuel to a chamber having a nozzle port which communicates by way of a supply line with the nozzle of the burner. A regulating valve disposed in the chamber normally closes the nozzle port but opens automatically shortly after start-up of the pump so as to enable pressurized fuel to be supplied to the nozzle. When the pump shuts down, the regulating valve is restored to its closed position.
A check valve is located closely adjacent the burner nozzle and cuts off flow from the supply line to the nozzle when the regulating valve closes. As a result of the check valve, fuel oil is trapped in the supply line and is prevented from dripping out of and building up on the nozzle and the burner.
When the regulating valve and the check valve are both closed, heat created either by the burner itself or by an electric preheater for the fuel supply line can cause a build up of pressure of the oil trapped in the supply line. If the pressure overcomes the check valve, fuel oil can undesirably drip out of the nozzle.
To prevent such dripping, certain prior systems have included a relief valve which opens and relieves the pressure in the supply line before such pressure can build up to a magnitude sufficient to open the check valve. The relief valves of prior systems are relatively complex and occupy significant space.